On Mon, Jan 11, 2010 at 6:30 PM, Grazvydas Ignotas <nota...@gmail.com> wrote:
> On Sat, Jan 9, 2010 at 6:42 AM, Khasim Syed Mohammed
> <kha...@beagleboard.org> wrote:
>> From cc1b24cb290d428f2e1aefec9c7878b46380f592 Mon Sep 17 00:00:00 2001
>> From: Syed Mohammed Khasim <kha...@ti.com>
>> Date: Sat, 9 Jan 2010 09:28:03 +0530
>> Subject: [PATCH] API to select twl4030 voltage and dev group
>>
>> Adds a new API "twl4030_pmrecv_vsel_cfg" to select voltage
>> and its device group
>>
>> Signed-off-by: Syed Mohammed Khasim <kha...@ti.com>
>> ---
>
> <snip>
>
>> @@ -113,3 +104,18 @@ void twl4030_power_mmc_init(void)
>> twl4030_i2c_write_u8(TWL4030_CHIP_PM_RECEIVER, byte,
>> TWL4030_PM_RECEIVER_VMMC1_DEDICATED);
>> }
>> +
>> +/*
>> + * Generic function to select Device Group and Voltage
>> + */
>> +void twl4030_pmrecv_vsel_cfg(u8 vsel_reg, u8 vsel_val,
>> + u8 dev_grp, u8 dev_grp_sel)
>> +{
>> + /* Select the Device Group */
>> + twl4030_i2c_write_u8(TWL4030_CHIP_PM_RECEIVER, dev_grp_sel,
>> + dev_grp);
>> +
>> + /* Select the Voltage */
>> + twl4030_i2c_write_u8(TWL4030_CHIP_PM_RECEIVER, vsel_val,
>> + vsel_reg);
>> +}
>
> I was always wondering why TI code first sets the device group (which
> effectively enables the supply), and configures voltage after that.
> Doesn't that cause wrong voltage output for a short interval of time
> (knowing that i2c transfers take some time to complete)? What happens
> if second write fails due to some i2c error?
>
Good / Wonderful Catch, I will correct them in my patch.
Regards,
Khasim
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